A California jury convicted respondent Pinholster on two counts of first-degree murder. At the penalty phase before the same jury, the prosecution produced eight witnesses, who testified about Pinholster’s history of threatening and violent behavior. Pinholster’s trial counsel, who unsuccessfully sought to exclude the aggravating evidence on the ground that the prosecution had not given Pinholster proper notice under California law, called only Pinholster’s mother. Counsel did not call a psychiatrist, though they had consulted with Dr. Stalberg, who had diagnosed Pinholster with antisocial personality disorder. The jury recommended the death penalty, and Pinholster was sentenced to death. Pinholster twice sought habeas relief in the California Supreme Court, alleging, inter alia, that his trial counsel had failed to adequately investigate and present mitigating evidence during the penalty phase. He introduced additional evidence to support his claim: school, medical, and legal records; and declarations from family members, one of his trial attorneys, and Dr. Woods, a psychiatrist who diagnosed him with bipolar mood disorder and seizure disorders, and who criticized Dr. Stalberg’s report. Each time, the State Supreme Court unanimously and summarily denied the claim on the merits. Subsequently, a Federal District Court held an evidentiary hearing and granted Pinholster federal habeas relief under 28 U. S. C. §2254. Affirming, the en banc Ninth Circuit considered the new evidence adduced in the District Court hearing and held that the State Supreme Court’s decision “involved an unreasonable application of . . . clearly established Federal law,” §2254(d)(1).

Held:

1. Review under §2254(d)(1) is limited to the record that was before the state court that adjudicated the claim on the merits. Pp. 8–14.

(a) As amended by the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA), §2254 sets several limits on a federal court’s power to grant habeas relief to a state prisoner. As relevant here, a claim that has been “adjudicated on the merits in State court proceedings,” “shall not be granted . . . unless the adjudication” “(1)resulted in a decision that was contrary to, or involved an unreasonable application of, clearly established Federal law,” or “(2) resulted in a decision that was based on an unreasonable determination of the facts in light of the evidence presented in the State court proceeding.”§2254(d). This “difficult to meet,” Harrington v. Richter, 562 U. S. ___, ___, and “ ‘highly deferential standard’ . . . demands that state court decisions be given the benefit of the doubt,” Woodford v. Visciotti, 537 U. S. 19, 24. Section 2254(d)(1)’s backward-looking language—“resulted in” and “involved”—requires an examination of the state-court decision at the time it was made. It follows that the record under review is also limited to the record in existence at that same time—i.e., the state-court record. This understanding is compelled by “the broader context of the statute as a whole,” which demonstrates Congress’ intent to channel prisoners’ claims first to state courts. Robinson v. Shell Oil Co., 519 U. S. 337, 341. It is also consistent with this Court’s precedents, which emphasize that §2254(d)(1) review focuses on what a state court knew and did. See, e.g., Lockyer v. Andrade, 538 U. S. 63, 71–72. Moreover, it is consistent with Schriro v. Landrigan, 550 U. S. 465, 474, which explained that a federal habeas court is “not required to hold an evidentiary hearing” when the state-court record “precludes habeas relief” under §2254(d)’s limitations. The Ninth Circuit wrongly interpreted Williams v. Taylor, 529 U. S. 420, and Holland v. Jackson, 542 U. S. 649, as supporting the contrary view. Pp. 8–12.

(b) This holding does not render superfluous §2254(e)(2)—which limits the federal habeas courts’ discretion to take new evidence in an evidentiary hearing. At a minimum, §2254(e)(2) still restricts their discretion in claims that were not adjudicated on the merits in state court. Although state prisoners may sometimes submit new evidence in federal court, AEDPA’s statutory scheme is designed to stronglydiscourage them from doing so. Pp. 13–14.

(c) Remand for a properly limited review is inappropriate here, because the Ninth Circuit ruled, in the alternative, that Pinholster merited habeas relief on the state-court record alone. P. 14.

2. On the record before the state court, Pinholster was not entitled to federal habeas relief. Pp. 14‘–31.

(a) To satisfy §2254(d)(1)’s “unreasonable application” prong, he must show that “there was no reasonable basis” for the State Supreme Court’s summary decision. Richter, supra, at ___. Pp. 15–16.

(b) Strickland v. Washington, 466 U. S. 668, provides the clearly established federal law here. To overcome the strong presumption that counsel has acted competently, id., at 690, a defendant must show that counsel failed to act “reasonabl[y] considering all the circumstances,” id., at 688, and must prove the “reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different,” id., at 694. Review here is thus “doubly deferential,” Knowles v. Mirzayance, 556 U.S. ___, ___, requiring a “highly deferential” look at counsel’s performance, Strickland, supra, at 689, through §2254(d)’s “deferential lens,” Mirzayance, supra, at ___, n. 2. Pp. 16–18.

(c) Pinholster has not shown that the State Supreme Court’s decision that he could not demonstrate deficient performance by his trial counsel necessarily involved an unreasonable application of federal law. Pp. 18–26.

(1) The state-court record supports the idea that his counsel acted strategically to get the prosecution’s aggravation witnesses excluded for lack of notice, and if that failed, to put on his mother as a mitigation witness. Billing records show that they spent time investigating mitigating evidence. The record also shows that they had an unsympathetic client who had boasted about his criminal history during the guilt phase, leaving them with limited mitigation strategies. In addition, when Dr. Stalberg concluded that Pinholster had no significant mental disorder or defect, he was aware of Pinholster’s medical and social history. Given these impediments, it would have been a reasonable penalty-phase strategy to focus on evoking sympathy for Pinholster’s mother. Pinholster has responded with only a handful of post-hoc nondenials by one of his lawyers. Pp. 18–23.

(2) The Ninth Circuit misapplied Strickland when it drew from this Court’s recent cases a “constitutional duty to investigate” and a principle that it was prima facie ineffective for counsel to abandon an investigation based on rudimentary knowledge of Pinholster’s background. Beyond the general requirement of reasonableness, “specific guidelines are not appropriate” under Strickland. 466 U. S., at 688. Nor did the Ninth Circuit properly apply the strong presumption of competence mandated by Strickland. Pp. 23–26.

(d) Even if his trial counsel had performed deficiently, Pinholster also has failed to show that the State Supreme Court must have unreasonably concluded that he was not prejudiced. Pp. 26–31.

(1) To determine “whether there is a reasonable probability that, absent the errors, the sentencer . . . would have concluded that” death was not warranted, Strickland, supra, at 695, the aggravating evidence is reweighed “against the totality of available mitigating evidence,” Wiggins v. Smith, 539 U. S. 510, 534. Here, the State presented extensive aggravating evidence at both the guilt and penalty phases. The mitigating evidence consisted primarily of the penalty-phase testimony of Pinholster’s mother and guilt-phase testimony given by his brother. After considering the evidence, the jury returned a sentence of death, which the state trial court found supported overwhelmingly by the weight of the evidence. Pp. 26–29.

(2) There is no reasonable probability that the additional evidence presented at Pinholster’s state proceedings would have changed the verdict. The “new” evidence largely duplicated the mitigation evidence of his mother and brother at trial. To the extent that there were new factual allegations or evidence, much of it is of questionable mitigating value. Dr. Woods’ testimony would have opened the door to rebuttal by a state expert; and new evidence relating to Pinholster’s substance abuse, mental illness, and criminal problems could lead a jury to conclude that he was beyond rehabilitation. The remaining new material in the state habeas record is sparse. Given what little additional mitigating evidence Pinholster presented in state habeas, the Court cannot say that the State Supreme Court’s determination was unreasonable. Pp. 29–30.

(3) Because this Court did not apply AEDPA deference to the question of prejudice in Williams v. Taylor, 529 U. S. 362, and Rompilla v. Beard, 545 U. S. 374, those cases lack the important “doubly deferential” standard of Strickland and AEDPA, and thus offer no guidance with respect to whether a state court has unreasonably determined that prejudice is lacking. Pp. 30–31.

590 F. 3d 651, reversed.

THOMAS, J., delivered the opinion of the Court, in which ROBERTS, C. J., and SCALIA and KENNEDY, JJ., joined in full; in which ALITO, J., joined as to all but Part II; in which BREYER, J., joined as to Parts I and II; and in which GINSBURG and KAGAN, JJ., joined as to Part II. ALITO, J., filed an opinion concurring in part and concurring in the judgment. BREYER, J., filed an opinion concurring in part and dissenting in part. SOTOMAYOR, J., filed a dissenting opinion, in which GINSBURG and KAGAN, JJ., joined as to Part II.